The filter presented is from 1994 but can be implemented with a more modern equivalent. We found this setting in the National Semiconductor Linear Applications Handbook.
The frequency of this oscillator can be set in a range from 5000 to 1. We found it in an old...
This indicator was found in a 1974 publication, but it can be fitted with the BC548 transistor or...
We found this amplifier in a 90's manual. The integrated circuit is not easy to obtain today. The...